Number of polygons of length 2n with 3 (self-avoiding polygon) holes on square lattice (not allowing rotations).

A056639

Number of polygons of length 2n with 3 (self-avoiding polygon) holes on square lattice (not allowing rotations).

Terms

    a(0) =62a(1) =3920a(2) =130560a(3) =3058544a(4) =56925214a(5) =900355884a(6) =12619939046a(7) =161208191596

External references